PlzNavigate: Speculatively spawns a renderer process for navigations.

content/browser/frame_host/render_frame_host_manager.cc

Index: content/browser/frame_host/render_frame_host_manager.cc
diff --git a/content/browser/frame_host/render_frame_host_manager.cc b/content/browser/frame_host/render_frame_host_manager.cc
index 49b9495e32d2cb4d0da64a6b03a606afce8c3006..2086703305b9204d398449b83ec8289807e06e0b 100644
--- a/content/browser/frame_host/render_frame_host_manager.cc
+++ b/content/browser/frame_host/render_frame_host_manager.cc
@@ -69,6 +69,11 @@ RenderFrameHostManager::~RenderFrameHostManager() {
   if (pending_render_frame_host_)
     CancelPending();
 
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableBrowserSideNavigation)) {
+    CleanUpSpeculativeRenderFrameHost();
+  }
+
   // We should always have a current RenderFrameHost except in some tests.
   SetRenderFrameHost(scoped_ptr<RenderFrameHostImpl>());
 
@@ -307,6 +312,10 @@ void RenderFrameHostManager::OnBeforeUnloadACK(
       // Current page says to cancel.
       CancelPending();
       cross_navigation_pending_ = false;
+      if (CommandLine::ForCurrentProcess()->HasSwitch(
+              switches::kEnableBrowserSideNavigation)) {
+        CleanUpSpeculativeRenderFrameHost();
+      }
     }
   } else {
     // Non-cross site transition means closing the entire tab.
@@ -321,6 +330,10 @@ void RenderFrameHostManager::OnBeforeUnloadACK(
       if (pending_render_frame_host_) {
         CancelPending();
         cross_navigation_pending_ = false;
+        if (CommandLine::ForCurrentProcess()->HasSwitch(
+                switches::kEnableBrowserSideNavigation)) {
+          CleanUpSpeculativeRenderFrameHost();
+        }
       }
 
       // This is not a cross-site navigation, the tab is being closed.
@@ -419,6 +432,16 @@ void RenderFrameHostManager::ClearNavigationTransitionData() {
 
 void RenderFrameHostManager::DidNavigateFrame(
     RenderFrameHostImpl* render_frame_host) {
+  DCHECK(render_frame_host);
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableBrowserSideNavigation)) {
+    if (speculative_render_frame_host_.get() == render_frame_host) {
+      CommitPending(true);
+      return;
+    }
+    CleanUpSpeculativeRenderFrameHost();
+  }
+
   if (!cross_navigation_pending_) {
     DCHECK(!pending_render_frame_host_);
 
@@ -427,13 +450,13 @@ void RenderFrameHostManager::DidNavigateFrame(
 
     // Even when there is no pending RVH, there may be a pending Web UI.
     if (pending_web_ui())
-      CommitPending();
+      CommitPending(false);
     return;
   }
 
   if (render_frame_host == pending_render_frame_host_) {
     // The pending cross-site navigation completed, so show the renderer.
-    CommitPending();
+    CommitPending(false);
     cross_navigation_pending_ = false;
   } else if (render_frame_host == render_frame_host_) {
     // A navigation in the original page has taken place.  Cancel the pending
@@ -446,6 +469,10 @@ void RenderFrameHostManager::DidNavigateFrame(
   }
 }
 
+void RenderFrameHostManager::CancelNavigation() {
+  CleanUpSpeculativeRenderFrameHost();
+}
+
 void RenderFrameHostManager::DidDisownOpener(
     RenderFrameHost* render_frame_host) {
   // Notify all RenderFrameHosts but the one that notified us. This is necessary
@@ -559,6 +586,30 @@ void RenderFrameHostManager::SwapOutOldFrame(
   }
 }
 
+void RenderFrameHostManager::RecycleRenderFrameHost(
+    scoped_ptr<RenderFrameHostImpl> render_frame_host) {
+  // TODO(carlosk): this code is very similar to what can be found in
+  // SwapOutOldFrame and we should see that these are unified at some point.
+
+  // If the SiteInstance for the pending RFH is being used by others, don't
+  // delete the RFH, just swap it out and it can be reused at a later point.
+  SiteInstanceImpl* site_instance = render_frame_host->GetSiteInstance();
+  if (site_instance->HasSite() && site_instance->active_frame_count() > 1) {
+    // Any currently suspended navigations are no longer needed.
+    render_frame_host->CancelSuspendedNavigations();
+
+    RenderFrameProxyHost* proxy =
+        new RenderFrameProxyHost(site_instance, frame_tree_node_);
+    proxy_hosts_[site_instance->GetId()] = proxy;
+    render_frame_host->SwapOut(proxy);
+    if (frame_tree_node_->IsMainFrame())
+      proxy->TakeFrameHostOwnership(render_frame_host.Pass());
+  } else {
+    // We won't be coming back, so delete this one.
+    render_frame_host.reset();
+  }
+}
+
 void RenderFrameHostManager::MoveToPendingDeleteHosts(
     scoped_ptr<RenderFrameHostImpl> render_frame_host) {
   // |render_frame_host| will be deleted when its SwapOut ACK is received, or
@@ -594,6 +645,152 @@ void RenderFrameHostManager::ResetProxyHosts() {
   STLDeleteValues(&proxy_hosts_);
 }
 
+void RenderFrameHostManager::BeginNavigation(
+    const FrameHostMsg_BeginNavigation_Params& params,
+    const CommonNavigationParams& common_params) {
+  CHECK(CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableBrowserSideNavigation));
+  // If there is an ongoing navigation, just clean it up.

[clamy, 2014/11/14 10:11:09]

nit: s/just clean it up/cancel it

[carlosk, 2014/11/14 17:43:37]

Done.

+  CancelNavigation();
+
+  SiteInstance* current_instance = render_frame_host_->GetSiteInstance();
+  // TODO(carlosk): Replace the default values by the right ones.
+  scoped_refptr<SiteInstanceImpl> new_instance =
+      static_cast<SiteInstanceImpl*>(GetSiteInstanceForNavigation(
+          common_params.url, NULL, common_params.transition, false, false,
+          true));
+
+  if (new_instance.get() != current_instance) {
+    // Navigating to a new SiteInstance -> speculatively create a new RFH
+
+    // TODO(carlosk): what the TRACE_EVENT_INSTANT2 for New SiteInstance found
+    // in UpdateStateForNavigate be copied here?
+
+    bool success = CreateSpeculativeRenderFrameHost(
+        common_params.url, current_instance, new_instance.get());
+    if (!success)
+      return;
+  } else {
+    // Navigating to the same SiteInstance -> make sure the current RFH is alive
+    DCHECK(render_frame_host_->GetSiteInstance() == new_instance);
+    if (!render_frame_host_->render_view_host()->IsRenderViewLive()) {
+      // Recreate the opener chain.
+      int opener_route_id = delegate_->CreateOpenerRenderViewsForRenderManager(
+          render_frame_host_->GetSiteInstance());
+      if (!InitRenderView(render_frame_host_->render_view_host(),
+                          opener_route_id, MSG_ROUTING_NONE,
+                          frame_tree_node_->IsMainFrame())) {
+        return;
+      }
+    }
+  }
+  DCHECK(new_instance->GetProcess()->HasConnection());
+  DCHECK(new_instance->GetProcess()->GetBrowserContext());
+}
+
+bool RenderFrameHostManager::CreateSpeculativeRenderFrameHost(
+    const GURL& url,
+    SiteInstance* old_instance,
+    SiteInstance* new_instance) {
+  CHECK(new_instance);
+  CHECK_NE(old_instance, new_instance);
+
+  // TODO(carlosk): should also try to reuse the current web_ui
+  // (ShouldReuseWebUI)?
+  scoped_ptr<WebUIImpl> new_web_ui(delegate_->CreateWebUIForRenderManager(url));
+  // TODO(carlosk): confirm this next section copied from SetPendingWebUI
+  // is in fact needed... I need access to the respective navigation entry
+  // though.
+  // If we have assigned (zero or more) bindings to this NavigationEntry in the
+  // past, make sure we're not granting it different bindings than it had
+  // before.  If so, note it and don't give it any bindings, to avoid a
+  // potential privilege escalation.
+  // if (new_web_ui &&
+  //     bindings != NavigationEntryImpl::kInvalidBindings &&
+  //     new_web_ui->GetBindings() != bindings) {
+  //   RecordAction(
+  //       base::UserMetricsAction("ProcessSwapBindingsMismatch_RVHM"));
+  //   new_web_ui.reset();
+  // }
+
+  scoped_ptr<RenderFrameHostImpl> new_render_frame_host;
+
+  // Check if we've already created an RFH for this SiteInstance.  If so, try
+  // to re-use the existing one, which has already been initialized.  We'll
+  // remove it from the list of proxy hosts below if it will be active.
+  RenderFrameProxyHost* proxy = GetRenderFrameProxyHost(new_instance);
+  if (proxy && proxy->render_frame_host()) {
+    // Delete the existing RenderFrameProxyHost, but reuse the RenderFrameHost.
+    // Prevent the process from exiting while we're trying to use it.
+    new_render_frame_host = proxy->PassFrameHostOwnership();
+    new_render_frame_host->GetProcess()->AddPendingView();
+
+    proxy_hosts_.erase(new_instance->GetId());
+    delete proxy;
+
+    // When a new render view is created by the renderer, the new WebContents
+    // gets a RenderViewHost in the SiteInstance of its opener WebContents.
+    // If not used in the first navigation, this RVH is swapped out and is not
+    // granted bindings, so we may need to grant them when swapping it in.
+    if (new_web_ui && !new_render_frame_host->GetProcess()->IsIsolatedGuest()) {
+      int required_bindings = new_web_ui->GetBindings();
+      RenderViewHost* rvh = new_render_frame_host->render_view_host();
+      if ((rvh->GetEnabledBindings() & required_bindings) !=
+          required_bindings) {
+        rvh->AllowBindings(required_bindings);
+      }
+    }
+  } else {
+    // Create a new RenderFrameHost if we don't find an existing one.
+    new_render_frame_host =
+        CreateRenderFrameHost(new_instance, MSG_ROUTING_NONE, MSG_ROUTING_NONE,
+                              false, delegate_->IsHidden());
+    DCHECK(new_render_frame_host);
+    RenderViewHostImpl* rvh = new_render_frame_host->render_view_host();
+
+    // Prevent the process from exiting while we're trying to navigate in it.
+    // Otherwise, if the new RFH is swapped out already, store it.
+    new_render_frame_host->GetProcess()->AddPendingView();
+
+    // Ensure that we have created RFHs for the new RFH's opener chain if
+    // we are staying in the same BrowsingInstance. This allows the new RFH
+    // to send cross-process script calls to its opener(s).
+    int opener_route_id = MSG_ROUTING_NONE;
+    if (new_instance->IsRelatedSiteInstance(old_instance)) {
+      opener_route_id =
+          delegate_->CreateOpenerRenderViewsForRenderManager(new_instance);
+      if (CommandLine::ForCurrentProcess()->HasSwitch(
+              switches::kSitePerProcess)) {
+        // Ensure that the frame tree has RenderFrameProxyHosts for the new
+        // SiteInstance in all nodes except the current one.
+        frame_tree_node_->frame_tree()->CreateProxiesForSiteInstance(
+            frame_tree_node_, new_instance);
+      }
+    }
+
+    bool success = InitRenderView(rvh, opener_route_id, MSG_ROUTING_NONE,
+                                  frame_tree_node_->IsMainFrame());
+    if (success) {
+      if (frame_tree_node_->IsMainFrame()) {
+        // Don't show the main frame's view until we know it will be used.
+        rvh->GetView()->Hide();
+      } else {
+        // Init the RFH, so a RenderFrame is created in the renderer.
+        success = InitRenderFrame(new_render_frame_host.get());
+      }
+    }
+    if (!success)
+      return false;
+
+    render_frame_delegate_->RenderFrameCreated(new_render_frame_host.get());
+  }
+
+  DCHECK(new_render_frame_host->GetSiteInstance() == new_instance);
+  speculative_render_frame_host_.reset(new_render_frame_host.release());
+  speculative_web_ui_.reset(new_web_ui.release());
+  return true;
+}
+
 // PlzNavigate
 RenderFrameHostImpl* RenderFrameHostManager::GetFrameHostForNavigation(
       const GURL& url,
@@ -757,7 +954,8 @@ SiteInstance* RenderFrameHostManager::GetSiteInstanceForNavigation(
     SiteInstance* dest_instance,
     ui::PageTransition dest_transition,
     bool dest_is_restore,
-    bool dest_is_view_source_mode) {
+    bool dest_is_view_source_mode,
+    bool create_unbounded_site_instance) {
   SiteInstance* current_instance = render_frame_host_->GetSiteInstance();
   SiteInstance* new_instance = current_instance;
 
@@ -789,13 +987,9 @@ SiteInstance* RenderFrameHostManager::GetSiteInstanceForNavigation(
       dest_is_view_source_mode);
   if (ShouldTransitionCrossSite() || force_swap) {
     new_instance = GetSiteInstanceForURL(
-        dest_url,
-        dest_instance,
-        dest_transition,
-        dest_is_restore,
-        dest_is_view_source_mode,
-        current_instance,
-        force_swap);
+        dest_url, dest_instance, dest_transition, dest_is_restore,
+        dest_is_view_source_mode, current_instance, force_swap,
+        create_unbounded_site_instance);
   }
 
   // If force_swap is true, we must use a different SiteInstance.  If we didn't,
@@ -813,7 +1007,8 @@ SiteInstance* RenderFrameHostManager::GetSiteInstanceForURL(
     bool dest_is_restore,
     bool dest_is_view_source_mode,
     SiteInstance* current_instance,
-    bool force_browsing_instance_swap) {
+    bool force_browsing_instance_swap,
+    bool create_unbounded_site_instance) {
   NavigationControllerImpl& controller =
       delegate_->GetControllerForRenderManager();
   BrowserContext* browser_context = controller.GetBrowserContext();
@@ -828,10 +1023,16 @@ SiteInstance* RenderFrameHostManager::GetSiteInstanceForURL(
     return dest_instance;
   }
 
+  SiteInstanceImpl* current_site_instance =
+      static_cast<SiteInstanceImpl*>(current_instance);
+
   // If a swap is required, we need to force the SiteInstance AND
   // BrowsingInstance to be different ones, using CreateForURL.
-  if (force_browsing_instance_swap)
-    return SiteInstance::CreateForURL(browser_context, dest_url);
+  if (force_browsing_instance_swap) {
+    return CreateSiteInstanceForURL(browser_context, dest_url,
+                                    create_unbounded_site_instance,
+                                    current_site_instance);
+  }
 
   // (UGLY) HEURISTIC, process-per-site only:
   //
@@ -849,9 +1050,6 @@ SiteInstance* RenderFrameHostManager::GetSiteInstanceForURL(
     return current_instance;
   }
 
-  SiteInstanceImpl* current_site_instance =
-      static_cast<SiteInstanceImpl*>(current_instance);
-
   // If we haven't used our SiteInstance (and thus RVH) yet, then we can use it
   // for this entry.  We won't commit the SiteInstance to this site until the
   // navigation commits (in DidNavigate), unless the navigation entry was
@@ -873,28 +1071,36 @@ SiteInstance* RenderFrameHostManager::GetSiteInstanceForURL(
         RenderProcessHostImpl::GetProcessHostForSite(browser_context, dest_url);
     if (current_site_instance->HasRelatedSiteInstance(dest_url) ||
         use_process_per_site) {
-      return current_site_instance->GetRelatedSiteInstance(dest_url);
+      return GetRelatedSiteInstanceForURL(current_site_instance, dest_url,
+                                          create_unbounded_site_instance);
     }
 
     // For extensions, Web UI URLs (such as the new tab page), and apps we do
     // not want to use the current_instance if it has no site, since it will
     // have a RenderProcessHost of PRIV_NORMAL.  Create a new SiteInstance for
     // this URL instead (with the correct process type).
-    if (current_site_instance->HasWrongProcessForURL(dest_url))
-      return current_site_instance->GetRelatedSiteInstance(dest_url);
+    if (current_site_instance->HasWrongProcessForURL(dest_url)) {
+      return GetRelatedSiteInstanceForURL(current_site_instance, dest_url,
+                                          create_unbounded_site_instance);
+    }
 
     // View-source URLs must use a new SiteInstance and BrowsingInstance.
     // TODO(nasko): This is the same condition as later in the function. This
     // should be taken into account when refactoring this method as part of
     // http://crbug.com/123007.
-    if (dest_is_view_source_mode)
-      return SiteInstance::CreateForURL(browser_context, dest_url);
+    if (dest_is_view_source_mode) {
+      return CreateSiteInstanceForURL(browser_context, dest_url,
+                                      create_unbounded_site_instance,
+                                      current_site_instance);
+    }
 
     // If we are navigating from a blank SiteInstance to a WebUI, make sure we
     // create a new SiteInstance.
     if (WebUIControllerFactoryRegistry::GetInstance()->UseWebUIForURL(
             browser_context, dest_url)) {
-        return SiteInstance::CreateForURL(browser_context, dest_url);
+      return CreateSiteInstanceForURL(browser_context, dest_url,
+                                      create_unbounded_site_instance,
+                                      current_site_instance);
     }
 
     // Normally the "site" on the SiteInstance is set lazily when the load
@@ -944,7 +1150,9 @@ SiteInstance* RenderFrameHostManager::GetSiteInstanceForURL(
   if (current_entry &&
       current_entry->IsViewSourceMode() != dest_is_view_source_mode &&
       !IsRendererDebugURL(dest_url)) {
-    return SiteInstance::CreateForURL(browser_context, dest_url);
+    return CreateSiteInstanceForURL(browser_context, dest_url,
+                                    create_unbounded_site_instance,
+                                    current_site_instance);
   }
 
   // Use the current SiteInstance for same site navigations, as long as the
@@ -962,6 +1170,51 @@ SiteInstance* RenderFrameHostManager::GetSiteInstanceForURL(
   // SiteInstance to a RenderViewHost (if it is different than our current
   // SiteInstance), so that it is ref counted.  This will happen in
   // CreateRenderView.
+  return GetRelatedSiteInstanceForURL(current_site_instance, dest_url,
+                                      create_unbounded_site_instance);
+}
+
+SiteInstance* RenderFrameHostManager::CreateSiteInstanceForURL(
+    BrowserContext* browser_context,
+    const GURL& dest_url,
+    bool create_unbounded_site_instance,
+    SiteInstanceImpl* current_instance) {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableBrowserSideNavigation)) {
+    if (create_unbounded_site_instance) {
+      return SiteInstance::Create(browser_context);
+    }
+    if (speculative_render_frame_host_) {
+      SiteInstanceImpl* sii = speculative_render_frame_host_->GetSiteInstance();
+      if (!sii->HasSite() && !sii->IsRelatedSiteInstance(current_instance)) {
+        return sii;
+      }
+    }
+  }
+
+  return SiteInstance::CreateForURL(browser_context, dest_url);
+}
+
+SiteInstance* RenderFrameHostManager::GetRelatedSiteInstanceForURL(
+    SiteInstanceImpl* current_instance,
+    const GURL& dest_url,
+    bool create_unbounded_site_instance) {
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableBrowserSideNavigation)) {
+    if (!current_instance->HasRelatedSiteInstance(dest_url)) {
+      if (create_unbounded_site_instance) {
+        return current_instance->GetRelatedEmptySiteInstance();
+      }
+      if (speculative_render_frame_host_) {
+        SiteInstanceImpl* sii =
+            speculative_render_frame_host_->GetSiteInstance();
+        if (!sii->HasSite() && sii->IsRelatedSiteInstance(current_instance)) {
+          return sii;
+        }
+      }
+    }
+  }
+
   return current_instance->GetRelatedSiteInstance(dest_url);
 }
 
@@ -1197,10 +1450,9 @@ bool RenderFrameHostManager::InitRenderView(
     }
   }
 
-  return delegate_->CreateRenderViewForRenderManager(render_view_host,
-                                                     opener_route_id,
-                                                     proxy_routing_id,
-                                                     for_main_frame_navigation);
+  return delegate_->CreateRenderViewForRenderManager(
+      render_view_host, opener_route_id, proxy_routing_id,
+      for_main_frame_navigation);
 }
 
 bool RenderFrameHostManager::InitRenderFrame(
@@ -1246,32 +1498,42 @@ int RenderFrameHostManager::GetRoutingIdForSiteInstance(
   return MSG_ROUTING_NONE;
 }
 
-void RenderFrameHostManager::CommitPending() {
+void RenderFrameHostManager::CommitPending(bool use_speculative_rfh) {
   TRACE_EVENT1("navigation", "RenderFrameHostManager::CommitPending",
                "FrameTreeNode id", frame_tree_node_->frame_tree_node_id());
+  // If use_speculative_rfh then kEnableBrowserSideNavigation must be enabled.
+  CHECK(!use_speculative_rfh ||
+        CommandLine::ForCurrentProcess()->HasSwitch(
+            switches::kEnableBrowserSideNavigation));
+
   // First check whether we're going to want to focus the location bar after
   // this commit.  We do this now because the navigation hasn't formally
   // committed yet, so if we've already cleared |pending_web_ui_| the call chain
   // this triggers won't be able to figure out what's going on.
   bool will_focus_location_bar = delegate_->FocusLocationBarByDefault();
 
-  // Next commit the Web UI, if any. Either replace |web_ui_| with
-  // |pending_web_ui_|, or clear |web_ui_| if there is no pending WebUI, or
-  // leave |web_ui_| as is if reusing it.
-  DCHECK(!(pending_web_ui_.get() && pending_and_current_web_ui_.get()));
-  if (pending_web_ui_) {
-    web_ui_.reset(pending_web_ui_.release());
-  } else if (!pending_and_current_web_ui_.get()) {
-    web_ui_.reset();
+  if (!use_speculative_rfh) {
+    DCHECK(!speculative_web_ui_);
+    // Next commit the Web UI, if any. Either replace |web_ui_| with
+    // |pending_web_ui_|, or clear |web_ui_| if there is no pending WebUI, or
+    // leave |web_ui_| as is if reusing it.
+    DCHECK(!(pending_web_ui_.get() && pending_and_current_web_ui_.get()));
+    if (pending_web_ui_) {
+      web_ui_.reset(pending_web_ui_.release());
+    } else if (!pending_and_current_web_ui_.get()) {
+      web_ui_.reset();
+    } else {
+      DCHECK_EQ(pending_and_current_web_ui_.get(), web_ui_.get());
+      pending_and_current_web_ui_.reset();
+    }
   } else {
-    DCHECK_EQ(pending_and_current_web_ui_.get(), web_ui_.get());
-    pending_and_current_web_ui_.reset();
+    web_ui_.reset(speculative_web_ui_.release());
   }
 
   // It's possible for the pending_render_frame_host_ to be NULL when we aren't
   // crossing process boundaries. If so, we just needed to handle the Web UI
   // committing above and we're done.
-  if (!pending_render_frame_host_) {
+  if (!pending_render_frame_host_ && !use_speculative_rfh) {
     if (will_focus_location_bar)
       delegate_->SetFocusToLocationBar(false);
     return;
@@ -1285,10 +1547,19 @@ void RenderFrameHostManager::CommitPending() {
 
   bool is_main_frame = frame_tree_node_->IsMainFrame();
 
-  // Swap in the pending frame and make it active. Also ensure the FrameTree
-  // stays in sync.
-  scoped_ptr<RenderFrameHostImpl> old_render_frame_host =
-      SetRenderFrameHost(pending_render_frame_host_.Pass());
+  scoped_ptr<RenderFrameHostImpl> old_render_frame_host;
+  if (!use_speculative_rfh) {
+    DCHECK(!speculative_render_frame_host_);
+    // Swap in the pending frame and make it active. Also ensure the FrameTree
+    // stays in sync.
+    old_render_frame_host =
+        SetRenderFrameHost(pending_render_frame_host_.Pass());
+  } else {
+    DCHECK(speculative_render_frame_host_);
+    old_render_frame_host =
+        SetRenderFrameHost(speculative_render_frame_host_.Pass());
+  }
+
   if (is_main_frame)
     render_frame_host_->render_view_host()->AttachToFrameTree();
 
@@ -1415,7 +1686,15 @@ RenderFrameHostImpl* RenderFrameHostManager::UpdateStateForNavigate(
 
   SiteInstance* current_instance = render_frame_host_->GetSiteInstance();
   scoped_refptr<SiteInstance> new_instance = GetSiteInstanceForNavigation(
-      url, instance, transition, is_restore, is_view_source_mode);
+      url, instance, transition, is_restore, is_view_source_mode, false);
+
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableBrowserSideNavigation) &&
+      speculative_render_frame_host_) {
+    if (speculative_render_frame_host_->GetSiteInstance() == new_instance)
+      return speculative_render_frame_host_.get();
+    CleanUpSpeculativeRenderFrameHost();
+  }
 
   const NavigationEntry* current_entry =
       delegate_->GetLastCommittedNavigationEntryForRenderManager();
@@ -1452,7 +1731,7 @@ RenderFrameHostImpl* RenderFrameHostManager::UpdateStateForNavigate(
         // navigate.  Just switch to the pending RFH now and go back to non
         // cross-navigating (Note that we don't care about on{before}unload
         // handlers if the current RFH isn't live.)
-        CommitPending();
+        CommitPending(false);
         return render_frame_host_.get();
       } else {
         NOTREACHED();
@@ -1557,29 +1836,23 @@ void RenderFrameHostManager::CancelPending() {
   // We no longer need to prevent the process from exiting.
   pending_render_frame_host->GetProcess()->RemovePendingView();
 
-  // If the SiteInstance for the pending RFH is being used by others, don't
-  // delete the RFH, just swap it out and it can be reused at a later point.
-  SiteInstanceImpl* site_instance =
-      pending_render_frame_host->GetSiteInstance();
-  if (site_instance->active_frame_count() > 1) {
-    // Any currently suspended navigations are no longer needed.
-    pending_render_frame_host->CancelSuspendedNavigations();
-
-    RenderFrameProxyHost* proxy =
-        new RenderFrameProxyHost(site_instance, frame_tree_node_);
-    proxy_hosts_[site_instance->GetId()] = proxy;
-    pending_render_frame_host->SwapOut(proxy);
-    if (frame_tree_node_->IsMainFrame())
-      proxy->TakeFrameHostOwnership(pending_render_frame_host.Pass());
-  } else {
-    // We won't be coming back, so delete this one.
-    pending_render_frame_host.reset();
-  }
+  RecycleRenderFrameHost(pending_render_frame_host.Pass());
 
   pending_web_ui_.reset();
   pending_and_current_web_ui_.reset();
 }
 
+void RenderFrameHostManager::CleanUpSpeculativeRenderFrameHost() {
+  CHECK(CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kEnableBrowserSideNavigation));
+  if (speculative_render_frame_host_) {
+    speculative_render_frame_host_->GetProcess()->RemovePendingView();
+    RecycleRenderFrameHost(speculative_render_frame_host_.Pass());
+  }
+  if (speculative_web_ui_)
+    speculative_web_ui_.reset();
+}
+
 scoped_ptr<RenderFrameHostImpl> RenderFrameHostManager::SetRenderFrameHost(
     scoped_ptr<RenderFrameHostImpl> render_frame_host) {
   // Swap the two.